Methods and systems for treating teeth

ABSTRACT

A system for repositioning teeth comprises a plurality of individual appliances used with braces. The appliances are configured to be placed successively on the patient&#39;s teeth and to incrementally reposition the teeth from an initial tooth arrangement, through a plurality of intermediate tooth arrangements, and to a final tooth arrangement. The appliances may be substituted with braces as appropriate to optimize the treatment of the teeth.

CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.14/594,624, filed Jan. 12, 2015, now U.S. Pat. No. 9,333,052, issued May10, 2016, which is a continuation of U.S. patent application Ser. No.14/155,236, filed Jan. 14, 2014, now U.S. Pat. No. 8,961,173, issuedFeb. 24, 2015, which is a continuation of U.S. patent application Ser.No. 11/971,496, filed Jan. 9, 2008, now U.S. Pat. No. 8,636,509, issuedJan. 28, 2014, which is a continuation of U.S. patent application Ser.No. 10/927,169, filed Aug. 25, 2004, now U.S. Pat. No. 7,326,051, issuedFeb. 5, 2008, which is a continuation of U.S. patent application Ser.No. 09/751,577, filed Dec. 29, 2000, now U.S. Pat. No. 7,074,038, issuedJul. 11, 2006, the entire contents of each of which are incorporated byreference.

RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.09/466,353, filed on Dec. 17, 1999, now U.S. Pat. No. 6,398,548, issuedJun. 4, 2002, the full disclosure of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention is related generally to the field of orthodontics.More particularly, the present invention is related to a method andsystem for repositioning teeth from an initial tooth arrangement to afinal tooth arrangement.

Tooth positioners for finishing orthodontic treatment are described byKesling in the Am. J. Orthod. Oral. Surg. 31:297-304 (1945) and32:285-293 (1946). The use of silicone positioners for the comprehensiveorthodontic realignment of a patient's teeth is described in Warunek etal. (1989)1 Clin. Orthod. 23:694-700. Clear plastic retainers forfinishing and maintaining tooth positions are commercially availablefrom Raintree Essix, Inc., New Orleans, La. 70125, and Tru-TainPlastics, Rochester, Minn. 55902. The manufacture of orthodonticpositioners is described in U.S. Pat. Nos. 5,186,623; 5,059,118;5,055,039; 5,035,613; 4,856,991; 4,798,534; and 4,755,139. The use oftwo or more vacuum-formed appliances for effecting orthodontic treatmentis suggested in Nahoum (1964)/V. Y. State D.J. 30:385-390.

Other publications describing the fabrication and use of dentalpositioners include Kleemann and Janssen (1996) J. Clin. Orthodon.30:673-680; Cureton (1996) J. Clin. Orthodon. 30:390-395; Chiappone(1980) J. Clin. Orthodon. 14:121-133; Shilliday (1971) Am. J.Orthodontics 59:596-599; Wells (1970) Am. J. Orthodontics 58:351-366;and Cottingham (1969) Am. J. Orthodontics 55:23-31.

Kuroda et al. (1996) Am. J. Orthodontics 110:365-369 describes a methodfor laser scanning a plaster dental cast to produce a digital image ofthe cast. See also U.S. Pat. No. 5,605,459.

U.S. Pat. Nos. 5,533,895; 5,474,448; 5,454,717; 5,447,432; 5,431,562;5,395,238; 5,368,478; and 5,139,419, assigned to Ormco Corporation,describe methods for manipulating digital images of teeth for designingorthodontic appliances.

U.S. Pat. No. 5,011,405 describes a method for digitally imaging a toothand determining optimum bracket positioning for orthodontic treatment.Laser scanning of a molded tooth to produce a three-dimensional model isdescribed in U.S. Pat. No. 5,338,198. U.S. Pat. No. 5,452,219 describesa method for laser scanning a tooth model and milling a tooth mold.Digital computer manipulation of tooth contours is described in U.S.Pat. Nos. 5,607,305 and 5,587,912. Computerized digital imaging of thejaw is described in U.S. Pat. Nos. 5,342,202 and 5,340,309. Otherpatents of interest include U.S. Pat. Nos. 5,549,476; 5,382,164;5,273,429; 4,936,862; 3,860,803; 3,660,900; 5,645,421; 5,055,039;4,798,534; 4,856,991; 5,035,613; 5,059,118; 5,186,623; and 4,755,139.

Recently, a new system for treating dental malocculsions has becomeavailable under the trade name Invisalign™ System. The Invisalign™System has two components. The first component is called ClinCheck® andallows practitioners to simulate treatment of teeth by observing andmodeling two-week stages of tooth movement. Based on the results of theClinCheck® component, the second component comprises aligners which arethin, clear, plastic removable dental appliances that correspond to eachtreatment stage of the ClinCheck® simulation. The aligners aremanufactured using advanced computer-controlled fabrication systems.Each aligner is worn by the patient for approximately two weeks beforeit is exchanged for a next stage aligner intended to further repositionthe teeth. The Invisalign™ System addresses many of the significantlimitations of conventional braces. In particular, the Invisalign™System aligners are virtually invisible, and are therefore moreaesthetically pleasing for the patient. Second, the aligners aregenerally less painful and uncomfortable than are traditional braces.Additionally, the aligners can be removed to permit conventional oralhygiene, thus being more healthy for the patient's teeth.

A present shortcoming of the Invisalign™ System, however, is that notall malocculsions can be effectively treated using the removablealigners. Certain tooth repositioning steps, such as extrusion, certainrotations, and the like, can be difficult to achieve with the presentInvisalign™ System. For those reasons, it would be desirable to provideimproved methods and systems for treating dental malocculsions which atleast partially retain the benefits and advantages of the removablealigners of the Invisalign™ System.

Information concerning the Invisalign™ System can be found at thewebsite of Align Technology, Inc. (www.invisalign.com). The Invisalign™System is described in U.S. Pat. No. 5,975,893, the full disclosure ofwhich is incorporated herein by reference. Other aspects of andpotential improvements of the Invisalign™ System are described in thefollowing published PCT applications and pending U.S. patentapplications, the full disclosures of which are incorporated herein byreference. They are as follows: Method and system for incrementallymoving teeth, filed Apr. 23, 1999, Ser. No. 09/298,268, and now U.S.Pat. No. 6,217,325; System and method for releasing tooth positioningappliances, filed Feb. 16, 1999, Ser. No. 09/250,962, and now U.S. Pat.No. 6,183,248; Composite articles and methods for destructive scanning,filed Sep. 25, 2000, Ser. No. 60/235,240; Manipulable dental modelsystem for fabrication of a dental appliance, filed Dec. 3, 1999, Ser.No. 09/454,786, and now U.S. Pat. No. 6,227,851; Attachment devices andmethods for a dental appliance, filed Dec. 3, 1999, Ser. No. 09/454,278,and now U.S. Pat. No. 6,309,215; System and method for producing toothmovement, filed Jan. 14, 2000, Ser. No. 09/483,071, and now U.S. Pat.No. 6,299,440; Systems and methods for varying elastic modulusappliances, filed Jul. 14, 2000, Ser. No. 09/616,830, and now U.S. Pat.No. 6,524,101; Embedded features and methods of a dental appliance,filed Jul. 14, 2000, Ser. No. 09/616,222, and now U.S. Pat. No.6,572,372; Methods and systems for modeling bite registration, filedApr. 25, 2000, Ser. No. 60/199,485; Modified tooth positioningappliances and methods and systems, filed Sep. 8, 2000, Ser. No.09/658,340, and now U.S. Pat. No. 6,497,574; Stress indicators for toothpositioning appliances, filed Jun. 30, 2000, Ser. No. 09/608,593, andnow U.S. Pat. No. 6,386,864; and Methods and systems for concurrenttooth repositioning and substance delivery, filed Sep. 21, 2000, Ser.No. 09/666,783, and now U.S. Pat. No. 6,607,382.

SUMMARY OF THE INVENTION

The present invention provides improved methods and systems forrepositioning teeth from an initial tooth arrangement to a final tootharrangement. The system for repositioning teeth comprises both polymericshell appliances and one or more wire and bracket appliance(s). Thepolymeric shell appliances are configured to be placed successively onthe patient's teeth and to incrementally reposition the teeth from abeginning tooth arrangement (which may or may not be the initial tootharrangement), through a plurality of intermediate tooth arrangements,and to a final tooth arrangement. The polymeric shell appliances will beused in combination with conventional wire and bracket “braces” asappropriate to effect full treatment of the teeth. The polymeric shellappliances, which may be aligners from the Invisalign™ System, may beused either before or after the wire and bracket appliance(s). Moreover,in some cases, it may be beneficial to intersperse treatment of thepatient with aligners for a period of time, with wire and bracketappliance(s) for a period of time, and then to repeat either or both ofthe polymeric shell appliance treatment and the wire and bracketappliance treatment. The particular order and/or repetition of treatmentmodalities may be selected depending on the particular patientrequirements.

Repositioning is accomplished with a system comprising a series ofpolymeric shell appliances configured to receive the teeth in a cavityand incrementally position the individual teeth in a series ofsuccessive steps. The polymeric shell appliances are used in connectionwith braces to effect a full course of tooth movement. The polymericshell appliances each have a geometry selected to reposition the teethfrom one arrangement to a subsequent arrangement. The appliancescomprise polymeric shells having cavities and the cavities of successiveshells have different geometries shaped to receive and resilientlyreposition teeth from the first to the second arrangement. One or morewire and bracket systems, usually referred to as “braces,” alsoreposition the teeth from one arrangement to a successive arrangement,the brackets and appliances being deployed in a preselected order toreposition teeth from the initial tooth arrangement to the final tootharrangement. Most often, the wire and bracket appliance(s) will beemployed first in order to partially reposition the teeth to bring thepatient within certain guidelines regarding the appropriate use of thepolymeric shell appliances. In other instances, it may be desirable toemploy the polymeric shell appliances first in order to achieve certaintreatment goals prior to finishing or further treatment with a wire andbracket appliance. The tooth positions defined by the cavities in eachsuccessive polymeric shell appliance differ from those defined by theprior appliance by no more than 2 mm, usually less than 1 mm, andtypically less than 0.5 mm. The system will include at least threepolymeric appliances, usually at least ten polymeric appliances,although complex cases involving many of the patient's teeth may taketwenty-five or more polymeric appliances.

An optional aspect of the present invention will be to provide criteriawhich enable the practitioner to distinguish between a less severemalocclusion and a more severe malocclusion. Generally, less severemalocculsions will be those in which it is expected that the patient maybe treated only with the polymeric shell appliances in order to achievea desired teeth reconfiguration. In contrast, patients who have a moresevere malocclusion (as determined in accordance with the criteria),will usually require a combination treatment using both polymeric shellappliances during one or more portions of the treatment and wire andbracket appliance(s) during one or more other portions of the treatment.Exemplary criteria are as follows.

-   -   (a) A-P correction of greater than 2 mm;    -   (b) Autorotation of the mandible required for vertical/A-P        correction;    -   (c) CR-CO discrepancy correction/treatment to other than centric        occlusion;    -   (d) Correction of moderate to severe rotations of premolars        and/or cannines that are greater than 20 degrees;    -   (e) Severe deep bite opened to ideal or open bite to be closed        to ideal;    -   (f) Extrusion of teeth greater than 1 mm other than as part of        torquing or in conjunction with intrading adjacent teeth;    -   (g) Teeth tipped by more than 45 degrees;    -   (h) Multiple missing teeth;    -   (i) Crowns less than 70% of normal size;    -   (j) Posterior open bite; and    -   (k) Movement of entire arch required for A-P correction.

Patients who meet none of the above criteria will usually be consideredto have malocclusions which can be treated using polymeric shellappliances without the need to employ wire and bracket appliance(s) atany point during treatment. In many instances, patients who have onlyone or two of the listed criteria may also be successfully treated usingpolymeric shell appliances alone. The decision may be based on thetreating professional's judgment, with patient consent, and may be basedon the particular patient's condition and prognosis.

According to a method of the present invention, a patient's teeth arerepositioned from an initial tooth arrangement to a final tootharrangement by successively placing one or more appliances havinggeometries selected to progressively reposition the teeth from a firstarrangement to successive arrangements. The current appliance can bereplaced with a new appliance or with one or more brackets toprogressively reposition the teeth, the brackets and appliances beingdeployed in seriatim to reposition teeth from the initial tootharrangement to the final tooth arrangement. The tooth positions definedby the cavities in each successive appliance differ from those definedby the prior appliance by no more than 2 mm. The successive placing stepmay include placing at least two to ten or possibly up to twenty-fiveadditional appliances. The appliances are successively replaced at aninterval in the range from two days to twenty days.

An improved method for repositioning teeth using appliances comprisespolymeric shells having cavities shaped to receive and resilientlyreposition teeth to produce a final tooth arrangement, wherein theimprovement comprises determining at the outset of treatment geometriesfor at least three appliances. The appliances are to be wornsuccessively by a patient to reposition teeth from an initial tootharrangement to the final tooth arrangement, wherein the cavities ofsuccessive shells have different geometries with at least fourgeometries with the potential for at least ten to twenty-five geometriesdetermined at the outset. The tooth positions defined by the cavities ineach successive appliance differ from those defined by the priorappliance by no more than 2 mm. In lieu of a successive appliance, oneor more braces can be used to move teeth.

As will be described in more detail below in connection with the methodsof the present invention, the systems may be planned and all individualappliances fabricated at the outset of treatment, and the appliances maythus be provided to the patient as a single package or system. The orderin which the appliances are to be used will be clearly marked, (e.g., bysequential numbering) so that the patient can place the appliances overhis or her teeth at a frequency prescribed by the orthodontist or othertreating professional. Unlike braces, the patient need not visit thetreating professional every time an adjustment in the treatment is made.While the patients will usually want to visit their treatingprofessionals periodically to assure that treatment is going accordingto the original plan, eliminating the need to visit the treatingprofessional each time an adjustment is to be made allows the treatmentto be carried out in many more, but smaller, successive steps whilestill reducing the time spent by the treating professional with theindividual patient. Moreover, the ability to use polymeric shellappliances that are more comfortable, less visible, and removable by thepatient, greatly improves patient compliance, comfort, and satisfaction.

In general, the transition to the next appliance or brace adjustment canbe based on a number of factors. Most simply, the appliances can bereplaced on a predetermined schedule or at a fixed time interval (i.e.number of days for each appliance) determined at the outset based on anexpected or typical patient response. Alternatively, actual patientresponse can be taken into account, e.g., a patient can advance to thenext appliance when that patient no longer perceives pressure on theirteeth from a current appliance, i.e. the appliance they have beenwearing fits easily over the patient's teeth and the patient experienceslittle or no pressure or discomfort on his or her teeth. In some cases,for patients whose teeth are responding very quickly, it may be possiblefor a treating professional to decide to skip one or more intermediateappliances, i.e. reduce the total number of appliances being used belowthe number determined at the outset. In this way, the overall treatmenttime for a particular patient can be reduced. In other situations, forpatients whose teeth do not respond as planned, braces may be used toreposition teeth.

In a particular aspect of the present invention, an improved method forrepositioning teeth utilizes both polymeric shell appliances havingcavities shaped to receive and resiliently reposition teeth and wire andbracket systems which are used sequentially with the polymeric shellappliances. Preferably, the wire and bracket system will be usedinitially to reposition the teeth prior to applying the polymeric shellappliances. For example, the wire and bracket system can be used tobring the patient to a tooth configuration within the criteria set forthabove. After the teeth are brought into within the criteria, thepolymeric shell appliances can be used to achieve a final tootharrangement, typically utilizing at least four appliances, more usuallyat least ten appliances, and often at least twenty-five appliances.

In a further aspect of the present invention, methods for treating adental malocclusion comprise providing criteria to distinguish between aless severe malocclusion and a more severe malocclusion. Exemplarycriteria have been set forth above. Whether an individual patient'smalocclusion is more or less severe is determined in accordance with thecriteria. Usually, patients who are free from all of the individualcriteria set forth above will be considered to have a less severemalocclusion, thereby indicating treatment with a plurality ofsuccessive polymeric shell appliances typically without any use of awire and bracket system. If, on the other hand, the malocclusion isdetermined to be more severe, the indicated treatment will include boththe use of the polymeric shell appliances as well as the use of a wireand bracket system. The treatment may occur in either order, with eitherthe polymeric shell appliances, or the wire and bracket system beingused first. The combined treatment, in either case, will be sufficientto reposition the teeth to a final desired arrangement.

A list may be provided in a variety of ways. Most commonly, the listwill be provided in written form, optionally as part of a “check list”which is filled out by the treating practitioner prior to commencingtreatment. The use of a check list helps assure compliance and permitsreview by others. In other cases, the list may be providedelectronically, e.g., over the web or on software provided to individualpractitioners. The use of an electronic list, particularly over the web,is useful since it permits updating of the criteria as additionalinformation is learned regarding treatment protocols.

Whether or not the malocclusion is more or less severe can be determinedin a variety of ways. Alternatively, determining whether themalocclusion is more or less severe may comprise obtaining a physical ordigital model of the patient's teeth, thus permitting remoteconsideration of the malocclusion. That is, the physical or digitalmodel can be transported to a central location for examination andevaluation. Physical models will typically be a casting taken directlyfrom the patient's teeth. Digital models may be obtained from suchcastings or alternatively may be obtained directly using intra-oralscanning techniques, such as those described in U.S. Pat. No. 4,935,635,the full disclosure of which is incorporated herein by reference.

This brief summary has been provided so that the nature of thedisclosure may be understood quickly. A more complete understanding ofthe disclosure can be obtained by reference to the following detaileddescription of the various embodiments thereof in connection with theattached drawings.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1A illustrates a patient's jaw and provides a general indication ofhow teeth may be moved by the methods and apparatus of the presentinvention.

FIG. 1B illustrates a single tooth from FIG. 1A and defines how toothmovement distances are determined.

FIG. 1C illustrates the jaw of FIG. 1A together with an incrementalposition adjustment appliance which has been configured according to themethods of the present invention.

FIG. 2 is a block diagram illustrating the steps of the presentinvention for producing a system of incremental position adjustmentappliances.

FIG. 3 is a block diagram setting forth the steps for manipulating aninitial digital data set representing an initial tooth arrangement toproduce a final digital data set corresponding to a desired final tootharrangement.

FIG. 4 is a flow chart illustrating an eraser tool for the methodsherein.

FIG. 4A illustrates the volume of space that is being erased by theprogram of FIG. 4.

FIG. 5 is a flow chart illustrating a program for matchinghigh-resolution and low-resolution components in the manipulation ofdata sets of FIG. 3.

FIG. 6 illustrates the method for generating multiple intermediatedigital data sets which are used for producing the adjustment appliancesof the present invention.

FIG. 7 illustrates alternative processes for producing a plurality ofappliances according to the methods of the present invention utilizingdigital data sets representing the intermediate and final appliancedesigns.

FIG. 8 is a flow chart illustrating one embodiment for treating teethwith appliances and braces.

FIG. 9 is a flow chart illustrating a second embodiment for treatingteeth with appliances and braces.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, systems and methods are provided forincrementally moving teeth using a plurality of discrete appliances,where each appliance successively moves one or more of the patient'steeth by relatively small amounts. The tooth movements will be thosenormally associated with orthodontic treatment, including translation inall three orthogonal directions relative to a vertical centerline,rotation of the tooth centerline in the two orthodontic directions(“root angulation” and “torque”), as well as rotation about thecenterline.

Referring now to FIG. 1A, a representative jaw 100 includes a pluralityof teeth 102. The present invention is intended to move at least some ofthese teeth from an initial tooth arrangement to a final tootharrangement. To understand how the teeth may be moved, an arbitrarycenterline (CL) is drawn through one of the teeth 102. With reference tothis centerline (CL), the teeth may be moved in the orthogonaldirections represented by axes 104, 106, and 108 (where 104 is thecenterline). The centerline may be rotated about the axis 108 (rootangulation) and 104 (torque) as indicated by arrows 110 and 112,respectively. Additionally, the tooth may be rotated about thecenterline. Thus, all possible free-form motions of the tooth can beperformed. Referring now to FIG. 1B, the magnitude of any tooth movementachieved by the methods and devices of the present invention will bedefined in terms of the maximum linear translation of any point P on atooth 102. Each point Pi will undergo a cumulative translation as thattooth is moved in any of the orthogonal or rotational directions definedin FIG. 1A. That is, while the point will usually follow a non-linearpath, there will be a linear distance between any point in the toothwhen determined at any two times during the treatment. Thus, anarbitrary point P_(I) may in fact undergo a true side-to-sidetranslation as indicated by arrow d₁, while a second arbitrary point P2may travel along an arcuate path, resulting in a final translation d₂.Many aspects of the present invention are defined in terms of themaximum permissible movement of a point P, induced by the methods in anyparticular tooth. Such maximum tooth movement, in turn, is defined asthe maximum linear translation of that point P, on the tooth whichundergoes the maximum movement for that tooth in any treatment step.

Referring now to FIG. 1C, systems according to the present inventionwill comprise a plurality of incremental position adjustment appliances.The appliances are intended to effect incremental repositioning ofindividual teeth in the jaw as described generally above. In a broadestsense, the methods of the present invention can employ any of the knownpositioners, retainers, or other removable appliances which are knownfor finishing and maintaining teeth positions in connection withconventional orthodontic treatment. The systems of the presentinvention, in contrast with prior apparatus and systems, will provide aplurality of such appliances intended to be worn by a patientsuccessively in order to achieve the gradual tooth repositioning asdescribed herein. A preferred appliance 100 will comprise a polymericshell having a cavity shaped to receive and resiliently reposition teethfrom one tooth arrangement to a successive tooth arrangement. Thepolymeric shell will preferably, but not necessarily, fit over all teethpresent in the upper or lower jaw. Often, only certain one(s) of theteeth will be repositioned while others of the teeth will provide a baseor anchor region for holding the repositioning appliance in place as itapplies the resilient repositioning force against the tooth or teeth tobe repositioned. In complex cases, however, many or most of the teethwill be repositioned at some point during the treatment. In such cases,the teeth which are moved can also serve as a base or anchor region forholding the repositioning appliance. Additionally, the gums and/or thepalette can serve as an anchor region, thus allowing all or nearly allof the teeth to be repositioned simultaneously.

The polymeric appliance 100 of FIG. 1C is preferably formed from a thinsheet of a suitable elastomeric polymeric, such as Tru-Tain. 0.03 in.thermal forming dental material, Tru-Tain Plastics, Rochester, Minn.55902. Usually, no wires or other means will be provided for holding theappliance in place over the teeth. In some cases, however, it will bedesirable or necessary to provide individual anchors on teeth withcorresponding receptacles or apertures in the appliance 100 so that theappliance can apply an upward force on the tooth which would not bepossible in the absence of such an anchor. Specific methods forproducing the appliances 100 are described hereinafter.

Referring now to FIG. 2, the overall method of the present invention forproducing the incremental position adjustment appliances for subsequentuse by a patient to reposition the patient's teeth will be described. Asa first step, a digital data set representing an initial tootharrangement is obtained, referred to hereinafter as the IDDS. The IDDSmay be obtained in a variety of ways. For example, the patient's teethmay be scanned or imaged using well known technology, such as X-rays,three-dimensional X-rays, computer-aided tomographic images or datasets, magnetic resonance images, etc. Methods for digitizing suchconventional images to produce data sets useful in the present inventionare well known and described in the patent and medical literature.Usually, however, the present invention will rely on first obtaining aplaster cast of the patient's teeth by well known techniques, such asthose described in Graber, Orthodontics: Principle and Practice, SecondEdition, Saunders, Philadelphia, 1969, pp. 401-415. After the toothcasting is obtained, it can be digitally scanned using a conventionallaser scanner or other range acquisition system to produce the IDDS. Thedata set produced by the range acquisition system may, of course, beconverted to other formats to be compatible with the software which isused for manipulating images within the data set, as described in moredetail below. General techniques for producing plaster casts of teethand generating digital models using laser scanning techniques aredescribed, for example, in U.S. Pat. No. 5,605,459, the full disclosureof which is incorporated herein by reference.

There are a variety of range acquisition systems, generally categorizedby whether the process of acquisition requires contact with the threedimensional object. A contact-type range acquisition system utilizes aprobe, having multiple degrees of translational and/or rotationalfreedom. By recording the physical displacement of the probe as it isdrawn across the sample surface, a computer-readable representation ofthe sample object is made. A non-contact-type range acquisition devicecan be either a reflective-type or transmissive-type system. There are avariety of reflective systems in use. Some of these reflective systemsutilize non-optical incident energy sources such as microwave radar orsonar. Others utilize optical energy. Those non-contact-type systemsworking by reflected optical energy further contain specialinstrumentation configured to permit certain measuring techniques to beperformed (e.g., imaging radar, triangulation and interferometry).

A preferred range acquisition system is an optical, reflective,non-contact-type scanner. Non-contact-type scanners are preferredbecause they are inherently nondestructive (i.e., do not damage thesample object), are generally characterized by a higher captureresolution and scan a sample in a relatively short period of time. Onesuch scanner is the Cyberware Model 15 manufactured by Cyberware, Inc.,Monterey, Calif.

Either non-contact-type or contact-type scanners may also include acolor camera, that when synchronized with the scanning capabilities,provides a means for capturing, in digital format, a colorrepresentation of the sample object. The importance of this furtherability to capture not just the shape of the sample object but also itscolor is discussed below.

The methods of the present invention will rely on manipulating the IDDSat a computer or workstation having a suitable graphical user interface(GUI) and software appropriate for viewing and modifying the images.Specific aspects of the software will be described in detailhereinafter. While the methods will rely on computer manipulation ofdigital data, the systems of the present invention comprising multipledental appliances having incrementally differing geometries may beproduced by non-computer-aided techniques. For example, plaster castsobtained as described above may be cut using knives, saws, or othercutting tools in order to permit repositioning of individual teethwithin the casting. The disconnected teeth may then be held in place bysoft wax or other malleable material, and a plurality of intermediatetooth arrangements can then be prepared using such a modified plastercasting of the patient's teeth. The different arrangements can be usedto prepare sets of multiple appliances, generally as described below,using pressure and vacuum molding techniques. While such manual creationof the appliance systems of the present invention will generally be muchless preferred, systems so produced will come within the scope of thepresent invention.

Referring again to FIG. 2, after the IDDS has been obtained, the digitalinformation will be introduced to the computer or other workstation formanipulation. In the preferred approach, individual teeth and othercomponents will be “cut” to permit their individual repositioning orremoval from the digital data. After thus “freeing” the components, theuser will often follow a prescription or other written specificationprovided by the treating professional. Alternatively, the user mayreposition them based on the visual appearance or using rules andalgorithms programmed into the computer. Once the user is satisfied withthe final arrangement, the final tooth arrangement is incorporated intoa final digital data set (FDDS).

Based on both the IDDS and the FDDS, a plurality of intermediate digitaldata sets (INTDDS's) are generated to correspond to successiveintermediate tooth arrangements. The system of incremental positionadjustment appliances can then be fabricated based on the INTDDS's, asdescribed in more detail below.

FIG. 3 illustrates a representative technique for manipulating the IDDSto produce the FDDS on the computer. Usually, the data from the digitalscanner will be in a high resolution form. In order to reduce thecomputer time necessary to generate images, a parallel set of digitaldata set representing the IDDS at a lower resolution will be created.The user will manipulate the lower resolution images while the computerwill update the high resolution data set as necessary. The user can alsoview/manipulate the high resolution model if the extra detail providedin that model is useful. The IDDS will also be converted into a quadedge data structure if not already present in that form. A quad edgedata structure is a standard topological data structure defined inPrimitives for the Manipulation of General Subdivisions and theComputation of Voronoi Diagrams, ACM Transactions of Graphics, Vol. 4,No. 2, April 1985, pp. 74-123. Other topological data structures, suchas the winged-edge data structure, could also be used.

As an initial step, while viewing the three-dimensional image of thepatient's jaw, including the teeth, gingivae, and other oral tissue, theuser will usually delete structure which is unnecessary for imagemanipulation and/or final production of an appliance. These unwantedsections of the model may be removed using an eraser tool to perform asolid modeling subtraction. The tool is represented by a graphic box.The volume to be erased (the dimensions, position, and orientation ofthe box) are set by the user employing the GUI. Typically, unwantedsections would include extraneous gum area and the base of theoriginally scanned cast. Another application for this tool is tostimulate the extraction of teeth and the “shaving down” of toothsurfaces. This is necessary when additional space is needed in the jawfor the final positioning of a tooth to be moved. The treatingprofessional may choose to determine which teeth will be shaved and/orwhich teeth will be extracted. Shaving allows the patient to maintaintheir teeth when only a small amount of space is needed. Typically,extraction and shaving, of course, will be utilized in the treatmentplanning only when the actual patient teeth are to be extracted and/orshaved prior to initiating repositioning according to the methods of thepresent invention.

Removing unwanted and/or unnecessary sections of the model increasesdata processing speed and enhances the visual display. Unnecessarysections include those not needed for creation of the toothrepositioning appliance. The removal of these unwanted sections reducesthe complexity and size of the digital data set, thus acceleratingmanipulations of the data set and other operations.

After the user positions and sizes the eraser tool and instructs thesoftware to erase the unwanted section, all triangles within the box setby the user will be removed and the border triangles are modified toleave a smooth, linear border. The software deletes all of the triangleswithin the box and clips all triangles which cross the border of thebox. This requires generating new vertices on the border of the box. Theholes created in the model at the faces of the box are re-triangulatedand closed using the newly created vertices.

The saw tool is used to define the individual teeth (or possibly groupsof teeth) to be moved. The tool separates the scanned image intoindividual graphic components enabling the software to move the tooth orother component images independent of remaining portions of the model.The saw tool defines a path for cutting the graphic image by using twocubic B-spline curves lying in space, possibly constrained to parallelplanes. A set of lines connects the two curves and shows the user thegeneral cutting path. The user may edit the control points on the cubicB-splines, the thickness of the saw cut, and the number of erasers used,as described below.

Thickness: When a cut is used to separate a tooth, the user will usuallywant the cut to be as thin as possible. However, the user may want tomake a thicker cut, for example, when shaving down surrounding teeth, asdescribed above. Graphically, the cut appears as the curve bounded byhalf the thickness of the cut on each side of the curve.

Number of Erasers: A cut is comprised of multiple eraser boxes arrangednext to each other as a piecewise linear approximation of the Saw Tool'scurve path. The user chooses the number of erasers, which determines thesophistication of the curve created—the greater the number of segments,the more accurately the cutting will follow the curve. The number oferasers is shown graphically by the number of parallel lines connectingthe two cubic 13-spline curves. Once a saw cut has been completelyspecified the user applies the cut to the model. The cut is performed asa sequence of erasings. A preferred algorithm is set forth in FIG. 4.FIG. 4A shows a single erasing iteration of the cut as described in thealgorithm.

A preview feature may also be provided in the software. The previewfeature visually displays a saw cut as the two surfaces that representopposed sides of the cut. This allows the user to consider the final cutbefore applying it to the model data set.

After the user has completed all desired cutting operations with the sawtool, multiple graphic solids exist. However, at this point, thesoftware has not determined which triangles of the quad edge datastructure belong to which components. The software chooses a randomstarting point in the data structure and traverses the data structureusing adjacency information to find all of the triangles that areattached to each other, identifying an individual component. Thisprocess is repeated starting with the triangle whose component is notyet determined. Once the entire data structure is traversed, allcomponents have been identified.

To the user, all changes made to the high resolution model appear tooccur simultaneously in the low resolution model, and vice versa.However, there is not a one-to-one correlation between the differentresolution models. Therefore, the computer “matches” the high resolutionand low resolution components as best as it can subject to definedlimits. The algorithm is described in FIG. 5.

After the teeth and other components have been placed or removed so thatthe final tooth arrangement has been produced, it is necessary togenerate a treatment plan, as illustrated in FIG. 6. The treatment planwill ultimately produce the series of INTDDS's and FDDS as describedpreviously. To produce these data sets, it is necessary to define or mapthe movement of selected individual teeth from the initial position tothe final position over a series of successive steps. In addition, itmay be necessary to add other features to the data sets in order toproduce desired features in the treatment appliances. For example, itmay be desirable to add wax patches to the image in order to definecavities or recesses for particular purposes. For example, it may bedesirable to maintain a space between the appliance and particularregions of the teeth or jaw in order to reduce soreness of the gums,avoid periodontal problems, allow for a cap, and the like. Additionally,it will often be necessary to provide a receptacle or aperture intendedto accommodate an anchor which is to be placed on a tooth in order topermit the tooth to be manipulated in a manner that requires the anchor,e.g., lifted relative to the jaw.

Some methods for manufacturing the tooth repositioning appliancesrequire that the separate, repositioned teeth and other components beunified into a single continuous structure in order to permitmanufacturing. In these instances, “wax patches” are used to attachotherwise disconnected components of the INTDDS's. These patches areadded to the data set underneath the teeth and above the gum so thatthey do not effect the geometry of the tooth repositioning appliances.The application software provides for a variety of wax patches to beadded to the model, including boxes and spheres with adjustabledimensions. The wax patches that are added are treated by the softwareas additional pieces of geometry, identical to all other geometries.Thus, the wax patches can be repositioned during the treatment path aswell as the teeth and other components.

In the manufacturing process, which relies on generation of positivemodels to produce the repositioning appliance, adding a wax patch to thegraphic model will generate a positive mold that has the same added waxpatch geometry. Because the mold is a positive of the teeth and theappliance is a negative of the teeth, when the appliance is formed overthe mold, the appliance will also form around the wax patch that hasbeen added to the mold. When placed in the patient's mouth, theappliance will thus allow for a space between the inner cavity surfaceof the appliance and the patient's teeth or gums. Additionally, the waxpatch may be used to form a recess or aperture within the appliancewhich engages an anchor placed on the teeth in order to move the toothin directions which could not otherwise be accomplished.

In addition to such wax patches, an individual component, usually atooth, can be scaled to a smaller or larger size which will result in amanufactured appliance having a tighter or looser fit, respectively.

Treatment planning is extremely flexible in defining the movement ofteeth and other components. The user may change the number of treatmentstages, as well as individually control the path and speed ofcomponents.

Number of Treatment Stages: The user can change the number of desiredtreatment stages from the initial to the target states of the teeth. Anycomponent that is not moved is assumed to remain stationary, and thusits final position is assumed to be the same as the initial position(likewise for all intermediate positions, unless one or more key framesare defined for that component).

Key frames: The user may also specify “key frames” by selecting anintermediate state and making changes to component position(s). Unlessinstructed otherwise, the software automatically linearly interpolatesbetween all user-specified positions (including the initial position,all key frame positions, and the target position). For example, if onlya final position is defined for a particular component, each subsequentstage after the initial stage will simply show the component an equallinear distance and rotation (specified by a quaternion) closer to thefinal position. If the user specifies two key frames for that component,it will “move” linearly from the initial position through differentstages to the position defined by the first key frame. It will thenmove, possibly in a different direction, linearly to the positiondefined by the second key frame. Finally, it will move, possibly in yeta different direction, linearly to the target position.

The user can also specify non-linear interpolation between the keyframes. A spline curve is used to specify the interpolating function ina conventional manner.

These operations may be done independently to each component, so that akey frame for one component will not affect another component, unlessthe other component is also moved by the user in that key frame. Onecomponent may accelerate along a curve between stages 3 and 8, whileanother moves linearly from stage 1 to 5, and then changes directionsuddenly and slows down along a linear path to stage 10. Thisflexibility allows a great deal of freedom in planning a patient'streatment.

Lastly, the software may incorporate and the user may at any point use a“movie” feature to automatically animate the movement from initial totarget states. This is helpful for visualizing overall componentmovement throughout the treatment process.

Above it was described that the preferred user interface for componentidentification is a three dimensional interactive GUI. Athree-dimensional GUI is also preferred for component manipulation. Suchan interface provides the treating professional or user with instant andvisual interaction with the digital model components. It is preferredover interfaces that permit only simple low-level commands for directingthe computer to manipulate a particular segment. In other words, a GUIadapted for manipulation is preferred over an interface that acceptsdirectives, for example, only of the sort: “translate this component by0.1 mm to the right.” Such low-level commands are useful forfine-tuning, but, if they were the sole interface, the processes ofcomponent manipulation would become a tiresome and time-consuminginteraction.

Before or during the manipulation process, one or more tooth componentsmay be augmented with template models of tooth roots. Manipulation of atooth model augmented with a root template is useful, for example, insituations where impacting of teeth below the gumline is a concern.These template models could, for example, comprise a digitizedrepresentation of the patient's teeth x-rays.

The software also allows for adding annotations to the datasets whichcan comprise text and/or the sequence number of the apparatus. Theannotation is added as recessed text (i.e. it is 3-D geometry), so thatit will appear on the printed positive model. If the annotation can beplaced on a part of the mouth that will be covered by a repositioningappliance, but is unimportant for the tooth motion, the annotation mayappear on the delivered repositioning appliance(s).

The above-described component identification and component manipulationsoftware is designed to operate at a sophistication commensurate withthe operator's training level. For example, the component manipulationsoftware can assist a computer operator, lacking orthodontic training,by providing feedback regarding permissible and forbidden manipulationsof the teeth. On the other hand, an orthodontist, having greater skillin intraoral physiology and teeth-moving dynamics, can simply use thecomponent identification and manipulation software as a tool and disableor otherwise ignore the advice.

Once the intermediate and final data sets have been created, theappliances may be fabricated as illustrated in FIG. 7. Preferably,fabrication methods will employ a rapid prototyping device 200 such as astereolithography machine. A particularly suitable rapid prototypingmachine is Model SLA-250/50 available from 3D System, Valencia, Calif.The rapid prototyping machine 200 will selectively harden a liquid orother non-hardened resin into a three-dimensional structure which can beseparated from the remaining non-hardened resin, washed, and used eitherdirectly as the appliance or indirectly as a mold for producing theappliance. The prototyping machine 200 will receive the individualdigital data sets and produce one structure corresponding to each of thedesired appliances. Generally, because the rapid prototyping machine 200may utilize a resin having non-optimum mechanical properties and whichmay not be generally acceptable for patient use, it will be preferred touse the prototyping machine to produce molds which are, in effect,positive tooth models of each successive stage of the treatment. Afterthe positive models are prepared, a conventional pressure or vacuummolding machine may be used to produce the appliances from a moresuitable material, such as 0.03 inch thermal forming dental material,available from Tru-Tain Plastics, Rochester, Minn. 55902. Suitablepressure molding equipment is available under the trade name BIOSTARfrom Great Lakes Orthodontics, Ltd., Tonawanda, N.Y. 14150. The moldingmachine 250 produces each of the appliances directly from the positivetooth model and the desired material. Suitable vacuum molding machinesare available from Raintree Essix, Inc.

After production, the plurality of appliances which comprise the systemof the present invention are preferably supplied to the treatingprofessional all at one time. The appliances will be marked in somemanner, typically by sequential numbering directly on the appliances oron tags, pouches, or other items which are affixed to or which encloseeach appliance, to indicate their order of use. Optionally, writteninstructions may accompany the system which set forth that the patientis to wear the individual appliances in the order marked on theappliances or elsewhere in the packaging. Use of the appliances in sucha manner will reposition the patient's teeth progressively toward thefinal tooth arrangement.

FIG. 8 illustrates a process 300 relating to a hybrid treatment forcomplex cases where a combination of appliances and braces may be used.Before treatment, at least one appointment is typically scheduled withthe orthodontist, dentist, and/or X-ray laboratory so that X-rays andphotographs of the patient's teeth and jaw structure can be taken. Alsoduring this preliminary meeting, or possibly at a later meeting, analginate mold of the patient's teeth is typically made. This moldprovides a model of the patient's teeth that the orthodontist uses inconjunction with the X-rays and photographs to formulate a treatmentstrategy and to produce appliances. The orthodontist then typicallyschedules one or more appointments during which appliances or braces canbe attached to the patient's teeth.

In the embodiment of FIG. 8, the patient is treated with the appliancessuch as the appliance 100 of FIG. 1C (step 302). The patient may wear aseries of appliances. For example, a treating professional such as anorthodontist may specify that the patient wear a new aligner every twoweeks. Periodically, the progress of the treatment is evaluated by thepatient's treating professional (step 304). If the patient isprogressing according to plan with the appliances, the next appliance inthe treatment sequence is provided to the patient and the process isrepeated (step 306). If the patient's progress is unsatisfactory, thetreating professional can consult with the patient to discuss treatmentoptions, including a hybrid treatment solution where alternative teethalignment devices are used in conjunction with the appliances to providea complete treatment. The devices can be full or partial braces,properly timed serial extractions, headgear, functional appliances, orother removable appliances.

If a hybrid treatment option is selected, the process continues withstep 308 wherein teeth straightening devices such as braces areinstalled. In one embodiment using braces, the treating professionalreviews the patient's record, attaches brackets and mounts braces to thepatient's teeth (step 308).

The braces may be removable or fixed (cemented and/or bonded to theteeth). They may be made of metal, ceramic or plastic. Molar bands areplaced over the molar teeth and cemented into place. The molar bandsusually have brackets welded or otherwise fixed thereon and thesebrackets provide an anchoring point for wires that pass throughadditional brackets cemented to the front teeth. The teeth surfaces areinitially treated with a weak acid. The acid optimizes the adhesionproperties of the teeth surfaces for brackets and bands that are to bebonded to them. The brackets and bands serve as anchors for otherappliances to be added later. After the acid step, the brackets andbands are cemented to the patient's teeth using a suitable bondingmaterial. No force-inducing appliances are added until the cement isset. For this reason, it is common for the orthodontist to schedule alater appointment to ensure that the brackets and bands are well bondedto the teeth. The primary force-inducing appliance in a conventional setof braces is the archwire. The archwire is resilient and is attached tothe brackets by way of slots in the brackets. The archwire links thebrackets together and exerts forces on them to move the teeth over time.Twisted wires or elastomeric 0-rings are commonly used to reinforceattachment of the archwire to the brackets. Attachment of the archwireto the brackets is known in the art of orthodontia as “ligation” andwires used in this procedure are called “ligatures.” The elastomeric0-rings are called “plastics.”

Once the braces have been installed, the progress of the brace treatmentprocess is periodically evaluated (step 310). Typically, these meetingsare scheduled every three to six weeks. The treating professionalperiodically tightens the braces to place a constant, gentle force in acarefully controlled direction and to move teeth through theirsupporting bone to a new desirable position (312). The patient's bracesmay be adjusted by installing a different archwire having differentforce-inducing properties or by replacing or tightening existingligatures. Alternatively, if the result of the evaluation at step 310indicates that the treatment is unsatisfactory, then the treatment planis reevaluated and the process of FIG. 8 can be repeated (step 314)until the teeth move to their intended destination.

FIG. 9 shows a process 320 that is similar to the process of FIG. 8, butincludes an option to use appliances after using the braces. Initially,the process 320 treats the teeth with appliances (step 322). Theprogress of the treatment is evaluated in step 324. If progress is madein a satisfactory manner in step 324, then the next appliance in thesequence is provided to the patient (step 326). If progress isunsatisfactory, then braces may be used. (step 328). Once the braceshave been installed, progress is then again evaluated (step 330).

From step 330, if progress is unacceptable, then step 336 allows for areevaluation of treatment plan.

If progress is satisfactory, then the braces may be tightened at step332. An option then is to reevaluate the progress to see if an appliancecan be used at step 334. If not, then the process continues back to step330 to treat the patient with braces. Alternatively, if the appliancecan be used, the process moves to step 322 to generate and deployappliances for treatment.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

What is claimed is:
 1. A method for generating a treatment plan forrepositioning a patient's teeth, the method comprising: scanning apatient's teeth with a non-contact-type scanner to form a digital dataset representative of a malocclusion of the patient's teeth; receiving,by a processor, the digital data set representative of the malocclusionof the patient's teeth, wherein the processor is configured to determineat least one of an A-P correction, CR-CO discrepancy, premolar rotation,canine rotation, and teeth extrusion; determining, by the processor, aseverity of the malocclusion based on the digital data set; andgenerating, by the processor, a treatment plan in response to thedetermined severity of the malocclusion, the treatment plan comprising afirst phase and a second phase administered to the patient in apre-selected order, wherein the first phase comprises placing a wire andbracket system on the teeth and the second phase comprises successivelyplacing a plurality of polymeric shell appliances on the teeth, theplurality of polymeric shell appliances having tooth receiving cavitieswith different geometries selected to reposition the teeth towards atarget arrangement.
 2. The method of claim 1, wherein determining theseverity of the malocclusion comprises determining whether themalocclusion is treatable with only polymeric shell appliances.
 3. Themethod of claim 2, wherein the treatment plan is generated in responseto a determination that the malocclusion is not treatable with onlypolymeric shell appliances.
 4. The method of claim 1, wherein theseverity of the malocclusion is determined based on one or morecriteria.
 5. The method of claim 4, wherein the one or more criteriacomprise one or more of: A-P correction of greater than 2 mm;autorotation of the mandible required for vertical/A-P correction; CR-COdiscrepancy correction/treatment to other than centric occlusion;correction of moderate to severe rotations of premolars and/or caninesthat are greater than 20 degrees; severe deep bite opened to ideal oropen bite to be closed to ideal; extrusion of teeth greater than 1 mmother than as part of torquing or in conjunction with intruding adjacentteeth; teeth tipped by more than 45 degrees; multiple missing teeth;crowns less than 70% of normal size; posterior open bite; or movement ofentire arch required for A-P correction.
 6. The method of claim 1,wherein the treatment plan is generated prior to placing the wire andbracket system and any of the plurality of polymeric shell appliances onthe teeth.
 7. The method of claim 1, wherein the treatment plancomprises a plurality of digital data sets representing a plurality ofintermediate tooth arrangements for repositioning the teeth towards thetarget arrangement.
 8. The method of claim 7, wherein the plurality ofintermediate tooth arrangements corresponds to the plurality ofpolymeric shell appliances.
 9. The method of claim 1, further comprisingtransmitting data to a fabrication machine for fabricating the pluralityof polymeric shell appliances.
 10. The method of claim 1, furthercomprising receiving evaluation data indicating whether repositioning ofthe teeth is progressing in a satisfactory fashion after the patient hasbeen administered the wire and bracket system or at least one polymericshell appliance of the plurality of polymeric shell appliances.
 11. Asystem for generating a treatment plan for repositioning a patient'steeth, the system comprising: a non-contact-type scanner; and a computerwith instructions stored therein that when executed cause the system to:receive a digital data set from the non-contact-type scanner, whereinthe digital data set represents a malocclusion of the patient's teeth,determine a severity of the malocclusion based on the digital data set;and generate a treatment plan in response to the determined severity ofthe malocclusion, the treatment plan comprising a first phase and asecond phase administered to the patient in a pre-selected order,wherein the first phase comprises placing a wire and bracket system onthe teeth and the second phase comprises successively placing aplurality of polymeric shell appliances on the teeth, the plurality ofpolymeric shell appliances having tooth receiving cavities withdifferent geometries selected to reposition the teeth towards a targetarrangement.
 12. The system of claim 11, wherein determining theseverity of the malocclusion comprises determining whether themalocclusion is treatable with only polymeric shell appliances.
 13. Thesystem of claim 12, wherein the treatment plan is generated in responseto a determination that the malocclusion is not treatable with onlypolymeric shell appliances.
 14. The system of claim 11, wherein theseverity of the malocclusion is determined based on one or morecriteria.
 15. The system of claim 14, wherein the one or more criteriacomprise one or more of: A-P correction of greater than 2 mm;autorotation of the mandible required for vertical/A-P correction; CR-COdiscrepancy correction/treatment to other than centric occlusion;correction of moderate to severe rotations of premolars and/or caninesthat are greater than 20 degrees; severe deep bite opened to ideal oropen bite to be closed to ideal; extrusion of teeth greater than 1 mmother than as part of torquing or in conjunction with intruding adjacentteeth; teeth tipped by more than 45 degrees; multiple missing teeth;crowns less than 70% of normal size; posterior open bite; or movement ofentire arch required for A-P correction.
 16. The system of claim 11,wherein the treatment plan is generated prior to placing the wire andbracket system and any of the plurality of polymeric shell appliances onthe teeth.
 17. The system of claim 11, wherein the treatment plancomprises a plurality of digital data sets representing a plurality ofintermediate tooth arrangements for repositioning the teeth towards thetarget arrangement.
 18. The system of claim 17, wherein the plurality ofintermediate tooth arrangements corresponds to the plurality ofpolymeric shell appliances.
 19. The system of claim 11, wherein theinstructions further cause the system to transmit data to a fabricationmachine for fabricating the plurality of polymeric shell appliances. 20.The system of claim 11, wherein the instructions further cause thesystem to receive evaluation data indicating whether repositioning ofthe teeth is progressing in a satisfactory fashion after the patient hasbeen administered the wire and bracket system or at least one polymericshell appliance of the plurality of polymeric shell appliances.